Water and Our Arid Climate Lecture Supplement

2 Water Is Essential for Life

3 Hydrologic Cycle

4 Annual Precipitation

5 Our Dry Climate We live in a semiarid land in the Los Angeles basin, which is a coastal desert. Rainfall averages less than 15 inches annually although it can be much less during droughts. The current drought is widespread—for the past few years, the Sierra Nevada snowpack, a major source of fresh water, has been well below normal.

6 Southern California’s Water Sources Much of the fresh water supply in Southern California is imported from the Sierra Nevada and Colorado River. The water supply in some communities is from the local mountains and deep wells. A few coastal cities are planning or constructing desalination plants to remove salt from seawater with reverse-osmosis, a costly and energy- intensive process.

7 Sierra Nevada Snowpack NASA Landsat satellite imagery Much of California’s population is heavily reliant on snowfall in the Sierra Nevada.

8 Sierra Nevada Ecosystems

9 Reservoir Levels, Fall

10 Sacramento Delta Water for 25 million Californians transits the Delta region located to the south of Sacramento.

11 Water Pumped from the Delta Near Dos Amigos, California The first stage on its way to the Los Angeles Basin.

12 California Aqueduct Interstate 5 to the west (left) The 300-mile trip.

13 Los Angeles Basin Digitally-enhanced image More than ten million people live in Los Angeles County (not including the other counties).

14 Hetch Hetchy Valley, Then Once known as the Grand Canyon of the Tuolumne, and a was considered the twin of Yosemite Valley. Early-1900’s

15 Hetch Hetchy Valley, Now Both images from O'Shaughnessy Dam, construction completed 1923 Hetch Hetchy supplies water and hydroelectric power to the greater San Francisco Bay area.

16 Los Angeles Aqueduct The City of Los Angeles also obtains water from the eastern slope of the Sierra Nevada.

17 Mono Lake From Conway Summit, looking south from U.S. Highway 395.

18 Tufa Formations Just to the east of Yosemite National Park, fresh water is diverted from Mono Lake into the Los Angeles aqueduct system.

19 Seagulls Morro Bay, California Many western seagulls nest at Mono Lake.

20 Food Web Mono Lake is a complex ecosystem including algae, shrimp, flies, and seagulls.

21 Is Mono Lake an ecological equivalent of the coal miner’s canary?

22 Receding Water Level Nesting seagulls on the islands in Mono Lake have been at risk due to the declining lake level resulting from water diversion.

23 The availability of low-cost water has fueled Southern California’s population growth since the early-1900s.

24 William Mulholland The architect and builder of Los Angeles’ first aqueduct.

25 Opening of the Gates “There it is—take it.” San Fernando Valley, November 5,

26 Los Angeles at Night, Then From Echo Mountain, above Altadena, circa Water from the Los Angeles Aqueduct made much of the urban and suburban growth possible.

27 Los Angeles at Night, Now The growth continues. From Mt. Wilson, above Altadena, recent photograph

28 Disaster Strikes St. Francis Dam, Collapse, March 12, 1928, 11:57 p.m. A wall of water rushed 40 miles to the ocean and caused a swath of destruction.

29 Historical Fiction “Chinatown” recounts the shenanigans of bringing water to Los Angeles in the early-20th century.

30 Drought-Resistant Gardening Many methods are available to reduce water usage. Your water district can provide ideas and even water-saving devices. One method is to plant vegetation at our homes, businesses, and public spaces that use much less water. This type of gardening is xeriscaping—it is becoming more common as water supplies diminish and water rates increase.

31 Xeriscaping

32 Information Sources Bookstores and websites are good sources of information about drought-resistant gardening.

33 Xeriscaping for Color

34 Desert Greenhouse

35 California Native Plants Theodore Payne Foundation Sun Valley, CA